正畸治疗中磨牙的拔除和保留(七)——拔除磨牙矫治成人骨性Ⅲ类错

Permanent molar extraction in correcting adult patient with Class Ⅲ malocclusion

目的:探讨采用拔除磨牙的方法矫治骨性Ⅲ类错牙合的疗效。方法:选择12例骨性Ⅲ类错牙合病例,生长发育均已完成。治疗前后拍摄头颅定位侧位片和口腔全景片。根据磨牙冠根发育状况,结合畸形类型设计拔除第一、第二或第三磨牙。采用直丝弓矫治技术,平均疗程20个月。选择15项软、硬组织头影测量指标,比较矫治前后软硬组织的变化,并进行t检验。结果:矫治前后SNA、SNB无明显改变、U1-LI显著增大、L1-MP显著减小,说明反牙合的矫治主要依赖于下前牙的内收直立实现,矫治后鼻唇角显著增大,颏唇角显著减小,使患者的侧貌得到明显改善。结论:对于生长发育完成的成人骨性Ⅲ类错牙合,选择拔除磨牙的矫治设计对于面型的改善及咬合关系的调整均有很好的效果。

Objective： To discuss treatment effect of the method which extracting permanent molar to correct the skeletal Class Ⅲ malocclusion. Method： Twelve patients with skeletal class Ⅲ malocclusion, whose growth has already completed, were included in the study. The average age was 20 years old, with age range from 15years old to 38 years old. Cephalometric films and panoramic x-rays were taken before and after the orthodontic treatment. According to the growth of crown-root and the healthy condition, combined with deformity type , design was carried out through extracting first,second or third molars. All cases were treated with straight-wire technique, the average treatment time was 20 months. 15 soft and hard tissure＇s cephalometric indexs were chose to compare the change of hard and soft tissue before and after treatment with the paired t test. Result：Around correction patient＇s SNA, SNB was not obvious changed, U1-LI remarkably increased as well as L1-MP remarkably reduced. This fully explained the correction of overbite mainly relies on uprighting and retroclinating of lower front teeth. After the correction nasolabial angle remarkably increased while mentolabial angle remarkably reduced which cause very big improvement to enable patient＇s side appearance. Conclusion： Adult patient of skeletal Class Ⅲ malocclusion as a result of already non- growth potential, can only adjust the tooth jaw relationship through tooth extraction. Design choosed extracting molars has been shown to be a effective way to improve the face shape and adjust the occlusal relationship.